Squamous cell carcinoma of the cervix is the most common type of cervical cancer, accounting for the majority of cases worldwide. This condition develops when abnormal changes occur in the flat, skin-like cells covering the outer surface of the cervix, typically in a specific area where two types of tissue meet.
Understanding Squamous Cell Carcinoma of the Cervix
Squamous cell carcinoma of the cervix is a cancer that begins in the squamous cells, which are thin, flat cells that cover the outer portion of the cervix called the ectocervix. The cervix itself is the lower, narrow part of the uterus that connects to the vagina, measuring approximately 2.5 centimeters in length. This cylindrical structure serves as the passageway between the upper reproductive organs and the vagina.[1]
Most cervical cancers originate in a particularly vulnerable area called the transformation zone, also known as the squamocolumnar junction. This is the border where the squamous cells of the outer cervix meet the column-shaped glandular cells that line the inner cervical canal. This zone is constantly undergoing cellular changes as part of normal bodily processes, which makes it more susceptible to abnormal cell growth that can eventually lead to cancer.[4]
Between 80 and 90 out of every 100 cervical cancers are squamous cell carcinomas, making it by far the most common type of cervical cancer. The remaining cases are typically adenocarcinomas, which develop in the glandular cells, or mixed types that contain features of both.[3][5]
How Common Is Squamous Cell Carcinoma of the Cervix?
Cervical cancer ranks as the fourth leading cause of cancer in women worldwide, following breast, lung, and colorectal cancer. Globally, there were approximately 661,021 new cases and 348,189 deaths from cervical cancer in 2022.[1][13]
In the United States, about 14,000 people receive a cervical cancer diagnosis each year, with approximately 4,320 deaths annually. Women between the ages of 35 and 44 are most likely to be diagnosed with this condition, though the average age of diagnosis is around 49 years.[3][13]
The distribution of cervical cancer cases varies dramatically across different regions of the world. In areas with well-established screening programs, the number of cases has decreased significantly over recent decades. However, approximately 70 percent of current cases occur in low and middle-income countries where comprehensive screening programs are not widely available or accessible to women who need them.[1][7]
What Causes Squamous Cell Carcinoma of the Cervix?
The overwhelming majority of cervical cancers, including squamous cell carcinomas, are caused by persistent infection with certain types of Human Papillomavirus, commonly known as HPV. This is a virus that spreads through skin-to-skin contact during sexual activity, including vaginal, anal, and oral sex. HPV serotypes 16 and 18 are considered high-risk types and are responsible for causing most cervical cancers.[1][3]
HPV infection is extremely common. Over 85 percent of the general population has been exposed to HPV at some point in their lives. Most people who become infected with HPV never realize it because their immune systems successfully fight off the infection without causing any symptoms or health problems. The virus typically clears from the body on its own within a year or two.[2][12]
However, when the body cannot eliminate a high-risk HPV infection and it persists for many years, it can cause changes in the cervical cells. These cellular changes progress through stages, starting with precancerous conditions called cervical intraepithelial neoplasia or CIN. The HPV virus alters the DNA in cervical cells, instructing them to multiply out of control and accumulate in abnormal growths. While not all precancerous changes progress to cancer, some will eventually develop into invasive squamous cell carcinoma if left untreated. This process typically takes several years, and in some cases up to a decade or more, though it can occasionally progress in less than a year.[7][13]
Who Is at Higher Risk?
While HPV infection is the primary cause of cervical cancer, not every woman who contracts HPV will develop cancer. Several factors can increase a person’s risk of developing squamous cell carcinoma of the cervix beyond the initial viral infection.[13]
One of the most significant controllable risk factors is not participating in regular cervical cancer screening. Women who have not had Pap tests at recommended intervals are much more likely to develop cervical cancer because precancerous changes go undetected and untreated. Having multiple sexual partners or having a sexual partner who has had many partners increases the risk of HPV exposure, though it only takes one sexual encounter to contract the virus.[3]
Cigarette smoking combined with HPV infection significantly increases cervical cancer risk. Tobacco use appears to damage the cervical cells’ DNA and weakens the body’s ability to fight HPV infections. Women who smoke and have HPV are more likely to develop precancerous changes that progress to cancer.[2][13]
Having a weakened immune system, whether from HIV infection, organ transplant medications, or other conditions that suppress immunity, makes it harder for the body to clear HPV infections. This allows the virus to persist longer and increases the chance of cellular changes leading to cancer. Long-term use of oral contraceptives for five years or more, combined with HPV infection, has also been associated with increased risk, though this risk decreases after stopping the medication.[2][13]
Reproductive factors also play a role. Women who have had three or more full-term pregnancies, those who had their first full-term pregnancy before age 20, or those who began having sexual intercourse at a young age face elevated risk. A personal or family history of cervical cancer, or a history of other sexually transmitted infections such as chlamydia, can also increase vulnerability to developing this cancer.[13]
Recognizing the Symptoms
One of the most challenging aspects of squamous cell carcinoma of the cervix is that early stages typically do not cause any symptoms. Women with precancerous changes or very early cancer usually feel completely normal, which is precisely why regular screening is so critical for early detection. As cancer develops and grows, symptoms gradually appear, though these may take considerable time to manifest.[3][10]
When symptoms of early-stage cervical cancer do develop, they often include unusual vaginal bleeding. This might occur after sexual intercourse, between menstrual periods, or after menopause when periods have already stopped. The bleeding might be light spotting or heavier flow. Many women also experience abnormal vaginal discharge that may be watery or bloody, heavier than usual, and potentially have an unpleasant odor.[3][10]
Pain during sexual intercourse, medically termed dyspareunia, is another common early warning sign. This discomfort occurs because the cancer affects the cervical tissues, making them sensitive and prone to bleeding or pain when touched.[10]
If the cancer spreads beyond the cervix to nearby tissues and organs, additional symptoms may develop. These can include difficult or painful urination, sometimes with blood visible in the urine. Some women experience diarrhea, pain, or bleeding from the rectum during bowel movements. More generalized symptoms might include persistent fatigue, unexplained weight loss, decreased appetite, and an overall feeling of being unwell. A dull, persistent backache or swelling in the legs can occur if the cancer affects lymph nodes or other structures. Pelvic or abdominal pain may also develop as the disease progresses.[3][10]
Prevention Strategies
Squamous cell carcinoma of the cervix is one of the most preventable cancers. Several effective strategies can significantly reduce the risk of developing this disease, and these approaches work best when used together.[1]
The HPV vaccine represents a powerful prevention tool. This vaccine protects against the high-risk HPV types that cause up to 90 percent of all cervical cancers. The vaccine is most effective when given before a person becomes sexually active and is potentially exposed to HPV. Health authorities typically recommend vaccination for girls and boys starting around age 11 or 12, though it can be given as early as age 9. The vaccine can also benefit young adults who were not previously vaccinated.[2][3]
Regular cervical cancer screening through Pap tests is perhaps the most proven prevention method. A Pap test, also called a Pap smear, involves collecting cells from the cervix to examine under a microscope for any abnormal changes. This screening can detect precancerous cellular changes long before they develop into invasive cancer. When these abnormal cells are found early, they can be removed or treated, preventing cancer from ever forming. Following recommended screening schedules is crucial for effective prevention.[1][3]
Practicing safer sex reduces the risk of HPV infection. Using condoms correctly and consistently from start to finish during every sexual encounter provides some protection against HPV transmission, though not complete protection since the virus can spread through skin-to-skin contact in areas not covered by condoms. Limiting the number of sexual partners and avoiding sexual contact with individuals who have had many partners or who have visible genital warts can also reduce exposure risk.[2][3]
Not smoking is another important preventive measure. Tobacco use not only increases cervical cancer risk in women with HPV but also hampers the body’s natural ability to clear the infection. Women who smoke should consider quitting, both to reduce cervical cancer risk and to improve overall health.[2][13]
How the Disease Develops
Understanding how squamous cell carcinoma develops helps explain why prevention and early detection are so effective. The process of cancer formation in the cervix follows a generally predictable pattern, though the timeline varies considerably from person to person.[13]
The transformation begins when high-risk HPV infects the squamous cells in the transformation zone of the cervix. The virus integrates its genetic material into the DNA of cervical cells, fundamentally altering the cells’ normal instructions. Instead of growing, dividing, and dying in an orderly fashion, these infected cells begin to multiply uncontrollably. The viral proteins interfere with the cell’s natural tumor-suppression mechanisms, allowing abnormal cells to survive and accumulate.[7]
Initially, these changes produce dysplasia, meaning abnormal cells appear in the cervical tissue but have not yet become cancerous. This precancerous condition is classified into grades based on how abnormal the cells look and how much of the cervical tissue is affected. Mild dysplasia often resolves on its own as the immune system clears the HPV infection. However, when dysplasia persists and becomes more severe, it can progress through increasingly serious stages.[4]
Eventually, if these abnormal cells are not removed, they break through the basement membrane, a thin layer that separates the surface cells from deeper tissues. At this point, the cancer becomes invasive. The malignant cells grow into the deeper layers of the cervix, which is composed mainly of fibroelastic connective tissue. From there, the tumor can extend into nearby structures. It may grow into the vaginal wall, infiltrate the tissues surrounding the cervix called the parametrium, or eventually reach the bladder in front of the cervix or the rectum behind it.[1][13]
Cancer cells can also spread through the lymphatic system, which serves as the body’s drainage network. The cervix drains to specific groups of lymph nodes, including the external iliac, internal iliac, and obturator lymph nodes. When cancer cells reach these lymph nodes, they can establish new tumor sites. In advanced cases, cancer may spread through the bloodstream to distant organs, a process called metastasis.[1]
What makes cervical cancer particularly amenable to prevention is the lengthy timeline of this progression. Longitudinal studies have shown that in patients with untreated precancerous changes, 30 to 70 percent will develop invasive carcinoma over a period of 10 to 12 years. This extended window provides numerous opportunities for screening to detect and treat abnormal cells before they become cancerous. However, it’s important to note that in approximately 10 percent of cases, the progression from precancerous changes to invasive cancer can occur in less than one year, highlighting the importance of regular screening rather than assuming there is always ample time.[13]
